Cathode ray sound recording



Jan. 9, 1934. w. D. cooLlDGE 1,943,109

CATHODE RAY SOUND RECORDING Filed Aug. 18. 1931 rigs.

y Inventor:

William DCoOldge,

His, Attorney.

Patented 9, 1934 @DE RAY SOUND RECORDMG `William D. Coolidge, Schenectady, N. Y., assignor to Gen Electric Company, a corporation of New York Application w l@ f iff-ew My invention relates to apparatus ior recording electrical variations by the use of cathode rays. More particularly it relates to cathode ray recording apparatus in which the rays are ejected from the evacuated generator in which they are producedand eiect the exposure of a member sensitive theretoarranged externally ci the generator. It is the object of my invention to provide an improved apparatus of this character l@ which is of simple form and which includes various features orn construction which facilitates the operation and maintenance of the apparatus and the production .therewith ci improved records.

My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. i is a combined 2o circuit diagram and side'elevation partly in sec tion of apparatus employing my invention; Fig. 2 is a detail of Fig. 1 drawn to a larger scale showing the cathode; Figs. 3 and i are details ci 1 also drawn to a larger scale showing the Lenard window through which the rays are ejected; and Fig. 5 shows a sample of lm having a sound record thereon made with the apparatus illustrated by Fig. i.

While my invention is applicable to the re- Se cording of electrical variations of various forms whether ci a continuous character or of a single momentary occurrence, I have chosen to illustrateit herein as arranged for the recording of variations corresponding to sound waves, in other words as a sound. recording apparatus. The cathode ray generating device or tube l is oi the type by which the cathode rays are ejected from the tube into the surrounding air. 1t is provided with the cathode 2 and anode 3 between 4.o which is applied the necessary high potential for the generation of the cathode rays by means, such icr exampletx as the step-up transformer e through the rectiiier 5, it being noted that the anode connection is througlci ground whereby e5 the danger and inconvenience to the operator because of the high voltage is avoided. The cathode is heated by means of the battery 6 under the control oi the rheostat 7. For the modulation of the cathode rays I have shown in the cathode anode circuit the electron discharge valve 9 whose cathode and plate elements con-l nect respectively with the rectier 5 and cathode 2. As the form of apparatus which I have i1- lustrated is adapted for the recording of voice or music, I have shown the sound pick-up device it. 193i. serial No. 557,935 (on. ita-icas) or microphone 10 connected through amplier 1-1 and transformer 12 with the cathode and `grid elements of the valve 9.

The anode 3 which is shown forming one end of the tube and which is secured to the body portion 13 in a vacuum tight manner is in the form. of a cylinder enclosing the cathode and having an outer end wall which is provided with the Lenard window 14 through which the cathode rays are ejected y:from the tube; The construction of this window may follow various forms, two preferred forms being represented in the drawing and described hereinafter.

in order that scattering of the ejected rays may be reduced to a minimum after passing through the Lenard window I have provided means either for introducing between the window and the light sensitive member, which in the present case is represented as the lm 15, a gas'consisting of some element of low density, such for example, as hydrogen, or for partially evacuating the space between the window and the light' sensitive meme ber. For this purposel have shownthe casing 16 whichyengages the end ofthe anode 3 and encloses that portion of the film opposite and immediately adjacent to the end of the anode containing the Lenard Window. The casing is shown provided with rolls 17 by'which the lm issupported so as to move past and close to the Lenard window it being understood that by suitable means, not shown, the film is caused to move at a uniform speed and is effectively shielded from light during the passage to and from the recording apparatus. Suitable means are provided in the lm slots 13 in the casing to close Aco lthe slots against the passage of gas or air yet without oering too great a resistance tothe movement ci the lm. I have shown the casing 16 provided with the connection 19 by which a suitable gas, such as hydrogen, may be introduced into the casing or by which the casing may be partly evacuated in which case the connection 19 will lead to suitable exhausting means.

Referring now to Fig. 3 where l have shown on a somewhat larger scale the outer end portion of the anode 3 and the Lenard window by which the cathode rays are ejected from the tube to expose the lrn l5, it will be seen that in the end Wall 21 of anode 3 I have provided the elongated or rectangular opening 22. Secured to the outer face of end wall 21, for example by soldering, is the member 23 which may be a metal foil, such as aluminum, which covers the opening 22. In that face of the member 23 adjacent to the anode I form the narrow channel 24 the 110 ico bottom of which hasl the' length and breadth corresponding to the cross-sectional dimensions .of the beam of cathode rays which are to be ejected from the tube and cause the exposure of the film. By the dotted lines 25 I have represented the area of the film exposed to the ejected rays. T his area may, for example, be .001 in width and .1"- in length. In order to facilitate the soldering of the member 23 to the anode I preferably construct this member having' a thickness of approximately .003 and'make the channel of such a depth that the material at the bottom thereof through which the rays areV ejected has a thickness of approximately .001". It will be noted that the exterior face of member 23 past which the iilm is adapted to be moved in veryl close relation is flat, the channel being formed on the inner face which is not exposed to dust and dirt. In this form of my invention also it will be noted that the width of the bottom of the channel determines the width of the ejected beam of rays, the opening 22 in the end wall of the anode having a materially greater width.

In the modified form represented by Fig. 4 the member 27 which is similar to member 23 of Fig. 3 and is similarly secured to the end wall of anode 3 is provided with channel 28 whose width is materially greater than the desired width of the ejected beam of rays. In this modiflcationv the width of the ejected beam is governed by the widthof the opening 29 in the end wall 21 of th anode which opening preferably is approximately .001" in width. In order to provide less thickness of material adjacent the opening 29 the end wall 2l is chamfered as at 30.

Inasmuch as the Lenard window 14 is long and narrow it is preferable that the cathode ray beam directed thereon shall have approximately the same form.' For this purpose I employ a line cathode 2, such cathode being y, shown as a rectangular trough-shaped member arranged parallel to the window and having the linear lament 31 arranged in the bottom thereof whereby the cathode rays produced thereby are focused on the Lenard window. vInstead of a linear fllament 31 I may employ a small diameter coil filament.

For the purpose of centering the beam of cathode rays on the window I provvide magnetic means, such for example as the permanent magnet 32 shown arranged externally of the tube and adapted to be adjusted in its mounting, not shown, so as to vary the position of the beam on the window.

I have chosen the particular 'embodiment ldescribed above as illustrative of my invention and it will be apparent thatvarious other modilcations may be made without departing from` the spirit and scope of my invention which modications I aim to cover by the appended claims. What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Apparatus for recording electrical variations comprising a cathode ray tube constructed to eject cathode rays therefrom, said tube having a narrow window through which the rays areejected on a member sensitive thereto, and having aline cathode arranged parallel with said window. 2. Apparatus for recording electrical variations .comprising a cathode ray tube' constructed to eject cathode rays therefrom on an external photographic member, said tube having a line focus cathode, means for modulating the rays in accordance with said variations, means for restricting the ejected rays to a narrow band parallel with the cathode, and means for.- centering the rays on said restricting means.

3. Apparatus for recording electrical variations on a photographic film comprising a cathode ray tube constructed to eject vthe cathode rays, said tube having a line cathode, and a narrow window parallel Awith the cathode through which the rays are ejected to the film, means for modulating the rays in accordance with the electrical variations and magnetic means for centeringv the rays from the line cathode on the window.

4. Apparatus for recording electrical variations comprising a cathode ray tube constructed to eject cathode rays, means for supporting a mem ber sensitive to said rays externally of the tube, and means for reducing the scattering of the rays between the tube and the member.

5. Apparatus for recording electrical variations comprising a cathode ray tube constructed to eject cathode rays, means for supporting a member sensitive to said rays externally of the tube, and means forproviding a medium between the tube and the member in which a reduced scattering of the rays occurs.

6. Apparatus for recording electrical variations comprising a cathode ray tube constructed to eject cathode rays, means for supporting a mem- .ber senstive to said rays externally of the tube in the path of the rays, and enclosing means for the member containing a gaseous medium whose density is less than that of air at atmospheri pressure.

7. Apparatus for recording electrical variations l opening for the passage of the cathode rays and a member secured to said anode over said opening having a portion of reduced thickness opposite said opening through which portion the rays are ejected.

9. In apparatus for recording electrical variations, a cathode ray tube havingy an anode form- ,ing a wall thereof and provided with an elongated opening for `the passage of the cathode rays and a member secured to the exterior of said anode over said opening having a ray transmitting channel formed in the face thereof adjacent to the anode.

10. In apparatus for recording electrical variations, a cathode ray tube having an anode forming a wall thereof and provided with an elongated opening for the passage of the cathode rays and a member secured to the exterior of said anode over said opening having a channel narrower than said opening formed in the member y011 that face thereof adjacent to the` anode.' 

